A hard floor cleaning device may include one or more high-speed rotating brushes. Each brush may have an elongate cylindrical core, extending axially between a first end and a second end, whose outer surface is covered with a brush material, e.g. soft microfiber filaments. The first and second ends of the brush may be bearingly mounted in the cleaning device so as to enable rotation of the brush around its axis, in particular when the latter is oriented parallel to and in abutment with a floor to be cleaned. The brush may typically be rotationally driven from one of its bearingly mounted ends, for which purpose the respective end may be detachably coupled to a transmission of an (electro)motor by means of a drive coupling assembly. The manner in which a brush is bearingly mounted in the hard floor cleaning device and coupled to the transmission may significantly effect its operating behavior.
For instance, it is known to mount a low-speed rotating brush, configured to be driven at a rotational speed of about 1,500 rpm, in a hard floor cleaning device by means of a drive coupling that includes an axial spring mechanism. The axial spring mechanism serves to take up axial play between the ends of the brush and brush mounting points of the cleaning device and to fix the brush's axial position between these mounting points (i.e. prevent travel of the brush through its range of axial play). This approach, however, does not appear suitable for mounting high-speed rotating brushes, which may be driven at rotational speeds of at least 2,500 rpm, e.g. at about 7,000 rpm. At such rotational speeds, slight imbalances in the mount of the brush may cause undesirably high levels of audible and sensible vibrations. To suppress these vibrations the clasping force exerted on the brush by the axial spring mechanism may be increased so as to stiffen the construction, but this also increases the risk of creep during the multiple-year life span of the device, and hence to further imbalances.